A process of cleaning a semiconductor substrate is one of the most important processes in a semiconductor device production process, and its importance has been increasingly higher as performance and a degree of integration in semiconductor device have also been becoming higher.
Conventionally, sulfuric acid, chloric acid, ammonia, hydrogen peroxide, hydrofruolic acid, or a mixture thereof have been used for removing impurities adhering to a surface of a semiconductor substrate. But it has been found as a result of a research conducted by the present inventors that the impurities can not completely be removed with these chemicals, and also that a surface of a semiconductor is corroded by these chemicals and minute irregularities are generated on the surface, and it has been confirmed that these phenomena give effects to device characteristics such as mobility of carrier and insulating performance of an oxide film formed on the surface. Accordingly, it has been desired to develop a cleaning method enabling complete removal of impurities without giving any damage to the semiconductor substrate for production of semiconductor devices with higher performance.
In addition, as the cleaning method based on the conventional technology required a long time and the cleaning steps are very complicated, and also as a vast quantity of chemicals or ultra-pure water is used, the cost is very large, and large scale facilities are required, so that price reduction of semiconductor devices has been prevented.
To solve the problems as described above, it is an object of the present invention to provide a cleaning method with extremely excellent cleaning effect which enables reduction in a quantity of chemicals and ultra-pure water used for cleaning and also which give no damage to a semiconductor substrate.